1. Field of the Invention
The present invention relates to a display apparatus comprising a plurality of light transmitting windows arranged in matrix form for defining display pixels, displays being made by controlling light transmission through the respective windows in response to display information. More particularly, the invention relates to a display apparatus as noted above, which includes a modulator for electrooptically modulating light passing through the respective light transmitting windows and controlling the amount of light passing through the windows by a combination of polarizers disposed at entry and exit sides, and a control device for controlling the modulator in response to the display information.
2. Description of the Prior Art
A known display apparatus of this type, as shown in FIGS. 7 and 8, comprises two polarizers 1 and 2 and a modulator 3 interposed therebetween. The modulator 3 includes a first optical element 10, an intermediate polarizer 11 and a second optical element 12. The first optical element 10 includes a plurality of light transmitting strips A1-An extending vertically and juxtaposed horizontally, and electrodes EA for forming electric fields to effect a 90-degree turn of a plane of polarization of light entering from the polarizer 1 for transmission through the respective light transmitting strips A1-An. The intermediate polarizer 11 allows passage only of the light entering from the first optical element 10 with the plane of polarization turned 90-degrees. The second optical element 12 includes a plurality of light transmitting strips B1-Bm extending horizontally and juxtaposed vertically, and electrodes EB for forming electric fields to effect a 90-degree turn of the plane of polarization of light entering from the intermediate polarizer 11 for transmission through the light transmitting strips B1-Bm. Thus, light transmitting windows are defined in matrix form by positions of overlapping between the light transmitting strips A1-An of the first optical element 10 and the light transmitting strips B1-Bm of the second optical element 12. (See Japanese Patent Publication Kokai No. 62-258429, for example.)
More particularly, when allowing passage of light through the light transmitting window at a selected coordinate position (p, q), electric fields are formed across the qth column light transmitting strip Aq of the first optical element 10 and the pth row light transmitting strip Bp of the second optical element 12. This electric field formation produces the following results:
(1) The first optical element 10 effect a 90-degree turn of the plane of polarization of only the light entering the qth column light transmitting strip Aq from the polarizer 1 at the entry side.
(2) The intermediate polarizer 11 allows passage of only the incident light from the qth light transmitting strip Aq with the plane of polarization turned 90 degrees.
(3) The second optical element 12 effects a 90-degree turn of the plane of polarization of only the light entering the pth row light transmitting strip Bp from the intermediate polarizer 11.
(4) The polarizer 2 at the exit side allows passage of only the incident light from the pth light transmitting strip Bp with the plane of polarization turned 90 degrees.
As noted above, the modulator of the known display apparatus has a three-piece construction consisting of two optical elements and one polarizer. This construction has the disadvantages of high manufacturing cost and a large thickness in the direction of light transmission.